Sex

The sex of a hymenopteran depends upon the amount of chromosomes it has.

Females come from fertilized eggs and have two sets of chromosomes, from a mother and a father.

Males come from unfertilized eggs and have one set of chromosomes, from a mother.

This arrangement is known as haplodiploidy.

Parthenogenesis is the term that describes reproduction in which only the female provides a genetic contribution.

Haplodiploidy creates a situation in which females are more closely related to their sisters than to their daughters.

On average, a female is likely to be 75% similar, genetically, to her sisters. This is because there is a 50% chance that she and her sisters will get the same genes from their mother, but a 100% chance that she and her sisters will obtain the same genes from their father.

However, a female is likely to be only 50% similar, on average, to her daughters, because she will give only half her genes to her daughter.

This means that, from an evolutionary standpoint, it is more advantageous for a female to help her mother produce more daughters (her sisters) than to care for daughters of her own.

Some entomologists think that this has encouraged hymenopterans to cooperate and ultimately, to developing complex social organizations.

Colonies of hymenopterans often consist of queens (reproducing females), drones (males) and workers (females that do not reproduce). The workers ensure the survival of their own genes by helping the colony to survive.

Army Ant

Army ants live in large colonies that are constantly moving.

They are predatory and engage in raids in which they attack a variety of animals, including snakes, lizards and small mammals and birds.

Gall Wasp

The female gall wasp lays her eggs on the stems, buds or leaves of a tree, often an oak tree.

When the larvae hatch, they secrete substances that irritate the tree. The tree forms galls - abnormal growths of tissue - around the areas that are irritated.

The larvae grow inside the galls. They become pupae will still inside the galls, and then eventually break out when they become adults.